I am looking to have a creature which is basically a small human sized bat, something like man-bat from the batman series. It would ideally fly or at least glide and would regularly hang upside down.

Assuming a human like form, I am worried about muscle strength holding up that much weight while having a light enough frame to glide, as well as blood rushing to the head. I want it to be as scientifically acceptable as possible to the point where it starts interfering significantly with basic humanoid tasks, where it will have to be hand-waved.

What biological features could I use to justify a bat-like creature of this size? Particularly issues of weight, bone strength, and blood rush when upside down.

  • $\begingroup$ If it has lightweight bones, for gliding, then it requires much less strength to hang, right? Isn't your problem a self solving one? $\endgroup$
    – Mołot
    Jan 14, 2018 at 12:42
  • $\begingroup$ Blood rush is a function of the arterial and venous valves. Giraffes have solved the same hydraulic problem for the opposite biological reason, so that wouldn't be an issue. $\endgroup$
    – pojo-guy
    Jan 14, 2018 at 13:44
  • $\begingroup$ Locking joints in the limbs that they use to grip? $\endgroup$
    – pojo-guy
    Jan 14, 2018 at 13:45
  • $\begingroup$ The giraffe thing was helpful @pojo-guy, I looked them up and it looks like quite a few features would work for this. $\endgroup$ Jan 15, 2018 at 1:57
  • $\begingroup$ @Mołot Do you think the bones could still be strong enough to still walk around as a humanoid? $\endgroup$ Jan 15, 2018 at 1:58

1 Answer 1


Sloths can do it.

sloth hanging upside-down

from https://nation.com.pk/24-Apr-2014/sloth-guts-designed-for-hanging

Three-toed sloths have a unique abdominal design - their innards fixed to their lower ribs to avoid squashing the lungs while hanging upside down, a study said Wednesday.

You could model your battish humanoid on sloths. I seem to recall they have other adaptations for the upside-down life like an immunity to arthritis.

  • $\begingroup$ That would be useful for lungs, though I'm not sure it would fix the large amount of blood that would be affected by gravity. $\endgroup$ Jan 15, 2018 at 1:26
  • $\begingroup$ @Wolfie but something helps sloths with their blood. You got a decent starting point, I guess you can just follow it. $\endgroup$
    – Mołot
    Jan 15, 2018 at 7:04

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